Wu Yan-Ling, Yang Qiu, Geng Hua-Yun, Cheng Yan
College of Physics, Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China.
National Key Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, CAEP, Mianyang 621900, China.
Phys Chem Chem Phys. 2024 Feb 22;26(8):6956-6966. doi: 10.1039/d3cp05613a.
The investigation and development of high thermoelectric value materials has become a research hotspot in recent years. In this work, based on the density functional theory on the Perdew-Burke-Ernzerhof (GGA-PBE) level, the thermoelectric properties of transition metal halides CdBr, Janus CdBrI, and CdI monolayers have been systematically investigated using Boltzmann transport theory. The calculation of the electronic band structure shows that these three materials have indirect band gap semiconductor properties. For carrier transport, the electron mobilities for CdBr, Janus CdBrI, and CdI monolayers are found to be 74, 16, 21 cm s V for p-type doping and 116, 102, 78 cm s V for n-type doping. Regarding their phonon transport, the CdBr, CdBrI, and CdI monolayers all have very low lattice thermal conductivity (4.78, 2.46, and 1.65 W m K, respectively) that decreases with increasing temperature, which is favorable for obtaining large values. The electrical transport results show that the performance of p-type doping is better than that of n-type doping. At 300 K, the Seebeck coefficients of p-type doping for the CdBr, CdBrI, and CdI monolayers are 217.72, 246.43, and 226.24 μV K, respectively. In addition, we predict that the values of the CdBr, CdBrI, and CdI monolayers are 0.62, 1.64, and 0.87 for p-type doping at 300 K respectively. The values increase with the increase of temperature. In particular, the Janus CdBrI monolayer has a value of 3.03 at 600 K. These results suggest that all these materials can be good candidates for thermoelectric materials.
近年来，高热电值材料的研究与开发已成为一个研究热点。在这项工作中，基于Perdew-Burke-Ernzerhof（GGA-PBE）水平的密度泛函理论，利用玻尔兹曼输运理论系统地研究了过渡金属卤化物CdBr、Janus CdBrI和CdI单层的热电性能。电子能带结构的计算表明，这三种材料具有间接带隙半导体特性。对于载流子输运，发现CdBr、Janus CdBrI和CdI单层的空穴迁移率在p型掺杂时分别为74、16、21 cm² V⁻¹ s⁻¹，在n型掺杂时分别为116、102、78 cm² V⁻¹ s⁻¹。关于它们的声子输运，CdBr、CdBrI和CdI单层都具有非常低的晶格热导率（分别为4.78、2.46和1.65 W m⁻¹ K⁻¹），且随温度升高而降低，这有利于获得较大的热电优值。电输运结果表明，p型掺杂的性能优于n型掺杂。在300 K时，CdBr、CdBrI和CdI单层p型掺杂的塞贝克系数分别为217.72、246.43和226.24 μV K⁻¹。此外，我们预测CdBr、CdBrI和CdI单层在300 K时p型掺杂的热电优值分别为0.62、1.64和0.87。热电优值随温度升高而增加。特别是，Janus CdBrI单层在600 K时的热电优值为3.03。这些结果表明，所有这些材料都可能是热电材料的良好候选者。
